The inkjet recording method is abruptly overspread and still making a progress, because the material cost is low, high-speed recording can be performed, noises are less generated at the recording and color recording is facilitated.
The inkjet recording method includes a continuous system of continuously jetting out a liquid droplet and an on-demand system of jetting out a liquid droplet according to image information signals, and the ejection system therefor includes a system of jetting out a liquid droplet by applying a pressure using a piezoelectric element, a system of jetting out a liquid droplet by generating bubbles in an ink under heat, a system using an ultrasonic wave, and a system of jetting out a liquid droplet by suction using an electrostatic force. With respect to the inkjet recording ink, an aqueous ink, an oily ink or a solid (fusion-type) ink is used.
The coloring agent used in such an inkjet recording ink is required to exhibit good solubility or dispersibility in a solvent, enable high-density recording, provide good color, be fast to light, heat and active gases in the environment (for example, oxidative gas (e.g., NOx, ozone) and SOx) and highly resistant against water and chemicals, ensure good fixing property and less blurring on an image-receiving material, give an ink having excellent storability, have high purity and no toxicity and be available at a low cost. However, it is very difficult to find out a coloring agent satisfying these requirements in a high level. In particular, a dye having good color hue and being fast to light, humidity and heat, especially at the printing on an image-receiving material having an ink-accepting layer containing a porous inorganic white pigment particle, being fast to oxidative gases in the environment, such as ozone, is strongly demanded.
As the dye for black color, a mixture of a disazo or trisazo dye with a yellow or magenta dye has been heretofore developed and for the raw material of these disazo and trisazo dyes, non-heterocyclic compounds such as phenol, naphthol, naphthylamine and aniline are being widely used. As for the disazo dye obtained from such raw materials, the dyes disclosed, for example, in European Patent No. 0761771 and Japanese Patent No. 2716541 are known, however, these dyes all are poor in the light fastness and furthermore, the fastness to oxidative gases such as ozone is extremely insufficient. Therefore, if such a dye is mixed with a yellow or magenta dye, the problem of poor light fastness or very insufficient fastness to oxidative gases such as ozone remains unsolved.